A humanoid robot, especially a biped locomotion robot, has being developed as an autonomous movement machine operable in environments where human beings have to execute difficult activities, such as care activity and in home and rescue activity in a fire scene. As shown in FIG. 1, such a robot is composed of an element system comprising a plurality of elements (head 101, body 102, and legs 103) which are under subordinative control of each other based on multiple joints, and an element relating system which relates the element system (joints 104, 105, 106, 107, 108, and 109 as 1-, 2- and 3-axis rotation systems). The whole control of the element system and the element relating system is described based on multiple variables belonging to each system and multiple parameters. However, it is difficult to separate independence and subordination between the multiple variables with high precision in the development phase. It is also difficult to describe a foot rising movement and a foot grounding movement that are associated with walking correctly.
When a theoretical walking movement and an actual walking movement do not coincide with each other, the cause of the discrepancy depends on some of the variables. Mechanical elements of the plurality of elements have physical parameters, and the rigidity and mass of each mechanical element have an important influence on the walking movement. For this reason, it is difficult to theoretically analyze whether the instability of control depends on the mass of the head or the rigidity of the body or leg. Additionally, it is difficult to analyze the discrepancy when each mechanical element is not manufactured according to theory.
Therefore, it is important to design a biped locomotion robot such that the changeable ranges of the parameters of all the elements are restricted in consideration of physical characteristics between the elements, for the purpose of facilitating the analysis and confirming the quality of the design. It is important to cause effective attenuation of influence between composite rotation systems. The definition of reasonable rules about the adjustment and initialization of a mechanical origin defining an initial condition of the movement is important to prove the quality of the design.